[Osteogenesis imperfecta. Reflections after the prenatal diagnosis of 2 cases]

The authors report two cases of prenatal diagnosis of osteogenesis imperfecta (OI) of type II according to the classification of Sillence. When dwarfism had been discovered with deformities, fractures and low bone density, the diagnosis was made in one case at 24 and the second at 20 weeks of amenorrhoea. A recent review of the literature shows that the ideas concerning OI have changed markedly recently. All agree that within the framework of classification of diseases that there is a single entity. A dominant autosome genetic transmission is increasingly considered to be the cause for all forms of the condition. The physiopathology of collagen makes it easier to understand why these should be clinical forms. The ability to localise deleterious genes by using molecular biology makes it likely a very early antenatal diagnosis will be possible. All the same, this optimism has to be tempered with the frequent discovery in this illness of mosaicism which still leaves a large place for ultrasound.